Brandywine GPS8 Plus User manual

MANUAL P/N 900000007 REV 2.0
User Guide
GPS Time and Frequency System
Model GPS8 Plus
P/N 071000003
Revision 2.0
October 2004
Brandywine Communications
2230 South Fairview Street
Santa Ana, CA 92704
[phone]
[phone]
http://www.brandywinecomm.com

MANUAL P/N 900000007 REV 2.0
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Revision History
REVISION DATE COMMENTS
1.9 09-16-04 Preliminary release of GPS8 Plus user guide.
2.0 10-11-04 Revision of entire user guide.

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Safety Warnings
WARNING: This unit contains lethal AC voltages.
Disconnect the unit from the AC supply before removing
the cover.
WARNING:
The lightning flash with an arrowhead inside of an equilateral triangle is
intended to alert the user to the presence of un-insulated “dangerous
voltage” within the product’s enclosure. The “dangerous voltage” may be
of sufficient magnitude to constitute as a risk of electrical shock to people.
CAUTION:
The exclamation point inside of an equilateral triangle is intended to alert
the user to the presence of important operation and maintenance
instructions in the user guide.

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Table of Contents
1Introduction ............................................................................................................................. 6
1.1 Scope of Section ............................................................................................................ 6
1.2 Purpose of Equipment.................................................................................................... 6
1.3 Specification ...................................................................................................................7
1.4 Controls, Indicators, and Connectors........................................................................... 11
2Installation............................................................................................................................. 13
2.1 Scope of Section .......................................................................................................... 13
2.2 Unpacking and Inspection............................................................................................ 13
2.3 Installation and Testing ................................................................................................ 13
3Operating Instructions........................................................................................................... 14
3.1 Scope of Section .......................................................................................................... 14
3.2 Operation...................................................................................................................... 14
3.3 Serial Communications ................................................................................................ 17
3.4 TxD1/RxD1 (Rear Panel J13) Baud Rate and Character Format................................ 18
3.5 TxD1/RxD1 (Rear Panel J13) User Commands and GPS8 Plus Responses ............. 19
3.6 Message Formats......................................................................................................... 22
3.6.1 Time and Date with Status, Position Averager Status, and Output Status ......... 22
3.6.2 Sounder Control .................................................................................................. 23
3.6.3 1
st
Pulse Output Data and Command (J10) ........................................................ 23
3.6.4 Dilution of Precision Values and Satellites Used................................................. 26
3.6.5 Time Code and Serial Data Output Formats ....................................................... 27
3.6.6 Frequency and Phase Controller Data ................................................................ 30
3.6.7 Health Status of Satellites ................................................................................... 36
3.6.8 Leap Second Information (Firmware 13+)........................................................... 37
3.6.9 2
nd
Pulse Output Data and Command (PCB CON6 Pin 3).................................. 38
3.6.10 Location and Signal Noise Ratio of Satellites...................................................... 39
3.6.11 Firmware Version Number................................................................................... 40
3.6.12 Offset of Local Time Data and Command........................................................... 41
3.6.13 Position of GPS Antenna..................................................................................... 42
3.6.14 Additional Information (Including Magnetic Declination) ..................................... 43
3.6.15 Request Precision Time ...................................................................................... 43
3.6.16 Software Reset Command .................................................................................. 44
3.7 TxD2/RxD2 Messages (Rear Panel J12) ..................................................................... 45
3.7.1 Type 1 Format ..................................................................................................... 45
3.7.2 Type 2 Format ..................................................................................................... 45
3.7.3 Type 3 Format (GPS4 Format)............................................................................ 47
3.8 IRIG B and AFNOR NF 2 87-500 Time Code Output .................................................. 48
3.8.1 IRIG B and AFNOR NF 2 87-500 Time Code Bit Allocation ............................... 49
3.9 NASA36 Time Code Output ......................................................................................... 51
3.10 2137 Time Code Output............................................................................................... 53
3.11 VELA Time Code Output (Slow Code)......................................................................... 54
3.12 Alarm Contacts (J14) ................................................................................................... 55
4GPS8 Plus Keypad and Display Operation .......................................................................... 56
4.1 Scope of Section .......................................................................................................... 56
4.2 General Principles of Operation of Keypad and Display.............................................. 56
4.3 Messages after Power On............................................................................................ 57
4.3.1 Operating Mode Selection ................................................................................... 58
4.3.2 GPS Locked Mode .............................................................................................. 58
4.3.3 Free Run Mode.................................................................................................... 59
4.3.4 1 PPS Lock Mode................................................................................................ 59
4.3.5 Manual Time and Date Entry............................................................................... 59
4.4 Position Screen ............................................................................................................ 60
4.5 Satellites Tracked Screen ............................................................................................ 60
4.6 1 PPS Status Screen ................................................................................................... 61
4.7 Mean Phase Screen..................................................................................................... 62
4.8 Estimated Mean Frequency ......................................................................................... 63

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4.9 Frequency Control........................................................................................................ 63
4.9.1 Test Configuration of Frequency Controller ........................................................ 64
4.10 Position Mode Configuration ........................................................................................ 64
4.10.1 Position Mode Selection ...................................................................................... 65
4.11 Local Time Configuration ............................................................................................. 65
4.11.1 Local Time Offset Adjustment ............................................................................. 65
4.12 Time Code Configuration ............................................................................................. 66
4.12.1 Time Code Selection ........................................................................................... 66
4.12.2 J13 TXD1 Configuration ...................................................................................... 67
4.12.3 J12 TXD2 Configuration ...................................................................................... 67
4.13 J10 Pulse Output Configuration ................................................................................... 68
4.13.1 J10 Timed Pulse Configuration ........................................................................... 68
4.13.2 J10 Pulse Period Configuration........................................................................... 69
4.13.3 J10 Pulse Time Code Configuration.................................................................... 70
4.14 Status Screen and Alarm Configuration 1.................................................................... 71
4.14.1 Selection of Alarm Masks 1................................................................................. 71
4.15 Status Screen and Alarm Configuration 2.................................................................... 72
4.15.1 Selection of Alarm Masks 2................................................................................. 72
4.16 Status Screen 3............................................................................................................ 73
4.17 Status Screen 4............................................................................................................ 73
5Principles of Operation.......................................................................................................... 74
5.1 Scope of Section .......................................................................................................... 74
5.2 Theory of Operation ..................................................................................................... 74
6Maintenance and Calibration ................................................................................................ 77
6.1 Scope of Section .......................................................................................................... 77
6.2 Routine Maintenance ................................................................................................... 77
6.3 Fault Finding................................................................................................................. 78
6.4 Oscillator Module.......................................................................................................... 78
7Diagrams............................................................................................................................... 79
8Appendix I Output Alarm Masks ........................................................................................... 86
9Appendix II Phase Noise....................................................................................................... 90

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1 Introduction
1.1 Scope of Section
Section 1 provides a general description of the GPS8 Plus. The introduction is
divided into three parts; purpose of the equipment, physical and electrical
specification, and an identification of the external controls, indicators, and
connectors.
1.2 Purpose of Equipment
The GPS8 Plus is a multi-output precision time and frequency standard that uses
the Global Positioning System (GPS) to steer and hold an internal oscillator and
clock system precisely on time. It is designed for use in telecommunications,
power utility, and military communication applications. Time and frequency
information is maintained to high accuracy by the internal oscillator even if no
satellites can be tracked. Each space vehicle in the GPS system transmits time,
frequency, and navigation information in two formats.
•P code: a precision code restricted to authorized users.
•C/A code: an unrestricted code available for general use.
In both cases the time information is maintained by the USA Department of
Defense and is traceable to the USA Naval Observatory. The standard GPS8
Plus uses the C/A code.
The GPS8 Plus provides a wide range of output options to form a complete time
and frequency management system. In addition, satellite data and navigational
information is outputted in the form of longitude, latitude, and altitude for
applications where precise positions must be known. For fixed position
operation, precise averaging of the position is carried out by the GPS8 Plus over
24 hours.

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1.3 Specification
SPECIFICATION DESCRIPTION OPTION
Satellite Signal GPS L1 1.57542 GHz
Satellite Code C/A 1.023 MHz
Receiver Type Parallel eight channels (8 satellites tracked
continuously and simultaneously)
Receiver Sensitivity -133 dBm
Input Impedance 50 ohm
Standard Antenna Active omni-directional 30 dB gain
Cold Start Requirement Automatic (no time or position input needed)
Typically 8 minutes to time synchronization
Satellite Acquisition Time Typically < 20 seconds (warm start)
Data Update Rate 1 per second
Timing Accuracy Tracking
Satellites (XTAL_1)
Within ±150 ns of GPS time
Standard deviation of 34 ns
Rubidium (Rb_2) oscillator
Better than 200 ns per hour
High stability OCXO (XTAL_1) oscillator
Better than 1 µs per hour
Standard OCXO (XTAL_2) oscillator
Better than 10 µs per hour
Timing Stability Tracking
No Satellites
Temperature Compensated Crystal Oscillator (TCXO)
Better than 120 µs per hour
Rubidium (Rb_2) disciplined oscillator
1 s 10 s 100 s 1000 s 10000 s 100000 s
3E-11 1E-11 3E-12 3E-12 2E-12 8E-13
Precision OCXO (XTAL_1) disciplined oscillator
1 s 10 s 100 s 1000 s 10000 s 100000 s
2E-12 3E-12 1E-11 1E-11 3E-12 1E-12
Standard OCXO (XTAL_2) disciplined oscillator
1 s 10 s 100 s 1000 s 10000 s 100000 s
1E-9 2E-10 3E-10 3E-10 3E-11 1E-12
-Frequency Accuracy
-Tracking At Least One
Satellite
Temperature Compensated (TCXO) disciplined
oscillator
1 s 10 s 100 s 1000 s 10000 s 100000 s
1.5E-9 5E-10 4E-10 3E-10 3E-11 1E-12
Rubidium oscillator (Rb_2)
5 x 10
-11
per month
High Stability OCXO (XTAL_1)
1 x 10
-10
per day after 30 days of operation
Standard OCXO (XTAL_2)
5 x 10
-9
per day after 30 days of operation
Frequency Stability
Tracking No Satellites
Temperature compensated (TCXO) oscillator
5 x 10
-9
per day after 30 days of operation

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SPECIFICATION DESCRIPTION OPTION
Static Operation Standard
Deviation Position Average
(measured in northern
hemisphere over sixteen
24 hours averaged
positions)
2.3 meters N/S 1.9 meters E/W 5.0 meters Vertical
Mobile Operation
Maximum Operational
Velocity
460 meters per second
Disciplined Oscillator
Control Resolution (Rb_2)
3 x 10
-14
SPECIFICATION DESCRIPTION OPTION
Power LED (green)
Fault LED (red)
Time Valid LED (green)
Tracking Satellites LED (green)
Monitoring/Status
Indicators
Reject Data LED (yellow)
Output Monitors 9 output monitor LEDs at each output socket for
present signal (and status available via TxD1/RxD1)
Sounder Selectable audible marker of GPS receiver 1 PPS,
Internal 1 PPS, or none
Antenna
Receiver
Initialization
Oscillator control
Oscillator frequency
Configuration parameters
Synthesizer phase-locked loop
RAM
Built In Test
FLASH/EPROM
Manual Controls Primary power switch
4 way keypad Data Entry Option
2 line LCD display
Instrument: -10 to +50°C
Operating Temperature
Range Antenna: -40 to +75°C
Humidity 95% non-condensing
Power Supply 115/230 VAC ±10% 45 - 65 Hz
48 VDC DC Supply Options
24 VDC
Power Consumption 10 W typically
Case 19” 1U rack mounting 12.01 inches deep
Weight 12 lbs typically

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INPUTS AND OUTPUTS REF DESCRIPTION OPTION
Telecom Frequency
Options
See
Below
E1 2.048 MHz
T1 1.544 MHz
Alarm J14
5-PIN din
180 DEG
Free contacts from status monitor
changeover relay and center contact can
be linked to + 5 V or 0 V internally
TxD1/RxD1 RS232 (OR RS422 user
selectable inside)
Port 1 J13
9 way D
socket User commands select and control output
types, request time data, frequency
controller data, GPS data, and instrument
output status
TxD2/RxD2 RS232 (OR RS422 user
selectable inside)
Port 2 J12
9 way D
socket Automatic 1 per second time and status
output OR output on receipt of user time
request
Carries 5 VDC at center pin for powered
antennas
GPS Ant J11
50R BNC
4 V output at 40 mA load
Option J10
50R BNC
One digital (DCLS 0 to 5 V from 50R) time
code same as selected modulated time
code or is 1
st
pulsed output
User selectable 1
st
pulse rate in place of
the time code
Selected time code or pulse level 0 to 5 V
from 50R source
1
st
Programmable Pulse
Output
-1 pulse per 2 ms to 1 pulse per day, with
1 ms to 9999 ms pulse duration active
high or active low
-1 pulse per day, active high 100 ms is
the default value
-Pulse time accuracy (on and off) is UTC
±150 ns
2
nd
Programmable Pulse
Output
PCB
ONLY
CON6
PIN 3
-1 pulse per 2 ms to 1 pulse per day, with
1 ms to 9999 ms pulse duration active
high or active low
-1 pulse per minute, active high 100 ms is
the default value
-Pulse time is 350 µs early
1 PPS J9
50R BNC
1 PPS, 0 to 5 V square wave from 50R
One user selectable modulated time code
IRIG B AFNOR NASA36 VELA 2137
Level 2.17 Vpp carrier high level from 10R
Maximum 1.7 Vpp into 50R (internally
adjustable)
Code J8
50R BNC
IRIG B is the default selection
8 KHz square wave (Telecom frame rate)8 KHz J7
75R BNC Square wave 0 to 5 V from 75R

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INPUTS AND OUTPUTS REF DESCRIPTION OPTION
Outputs are link selectable (internally)
with the following options:
Telecom (2.048 MHz or 1.544 MHz as
selected above)
1 MHz (internal jumper selection)
5 MHz (internal jumper selection)
10 MHz (internal jumper selection)
Output level 0 to 5 V from 75R
Telco (two) J6 & J5
75R BNC
Output level square wave 2.37 Vpp into
75R (G703 ¶ 6)
Outputs are from Bandpass filter module
2, specified at time of purchase, with the
following options:
Telecom (2.048 MHz or 1.544 MHz as
selected above)
1 MHz
5 MHz
10 MHz
Each output level 1 Vrms from 50R, 75R,
or 120R by internal jumper selection (50R
is the default)
Sine wave 3 Vpp from 75R meets G703 ¶
10
Transformer isolation (75R connector
grounded to case)
Frequency accuracy and holdover similar
to tables above
Meets primary reference clock
requirements G811
Harmonic distortion -30 dBc or better
Freq 2 (two) J4 & J3
75R BNC
5 MHz or 10 MHz phase noise, see
Appendix II
Outputs are from Bandpass filter module
2, specified at time of purchase, with the
following options:
Telecom (2.048 MHz or 1.544 MHz as
selected above)
1 MHz
5 MHz
10 MHz
Output level 1 Vrms from 50R
Frequency accuracy and holdover as per
tables above
Transformer isolation (50R isolated
connectors)
Harmonic distortion -30 dBc or better
Freq 1 (two) J2 & J1
50R BNC
5 MHz or 10 MHz phase noise, see
Appendix II